Oxygen sensor

Tiny
RANYRIZK
  • MEMBER
  • 2003 CADILLAC CTS
  • 129,000 MILES
Some times the rpm becomes very slow and the engine risks to turns off.
My scanner gave:
P0036
P0056
P0141
P0161.
Someone told me I have to change the ECM with the O2 sensor because usually the O2 sensor gave a high voltage that brakes a cicuit in the ECM is that true?
Or just I change the 4 O2 sensors and it is going to be OK?
Regads
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Monday, May 6th, 2013 AT 3:00 AM

1 Reply

Tiny
ASEMASTER6371
  • EXPERT
No, that is not true.

36

CIRCUIT DESCRIPTION
Heating elements inside the heated oxygen sensor (HO2S) minimize the time required for the sensors to reach operating temperature, and to provide an accurate voltage signal. A low side driver within the engine control module (ECM) is pulse width controlled to provide current to the heater elements. During warm-up the ECM will pulse the heaters ON-OFF to prevent thermal shock to the sensor components from moisture in the exhaust system. The ECM will not allow continuous HO2S heating until calibrated limits of time, temperature, and intake airflow have been reached. The ECM continuously monitors the HO2S heater current draw and operating state by briefly turning OFF the heater low side driver at regular intervals. A small reference voltage is present at the heater low control circuit. When the low side driver is commanded ON, the reference voltage is low, 2.6-4.6 volts. When the low side driver is commanded OFF, the reference voltage is high, close to battery voltage. If the ECM detects that the HO2S heater low control circuit voltage is between 2.6-4.6 volts when the heater is commanded OFF, DTCs P0030, P0036, P0050, or P0056 will set.

Each HO2S has the following circuits:
HO2S high signal
HO2S low signal
HO2S heater ignition 1 voltage
HO2S heater low control
CONDITIONS FOR RUNNING THE DTC
The engine is running.

CONDITIONS FOR SETTING THE DTC
The ECM detects that the HO2S heater low control circuit voltage is between 2.6-4.6 volts when the heater is commanded OFF, indicating an open HO2S heater circuit.

ACTION TAKEN WHEN THE DTC SETS
The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.

56

CIRCUIT DESCRIPTION
Heating elements inside the heated oxygen sensor (HO2S) minimize the time required for the sensors to reach operating temperature, and to provide an accurate voltage signal. A low side driver within the engine control module (ECM) is pulse width controlled to provide current to the heater elements. During warm-up the ECM will pulse the heaters ON-OFF to prevent thermal shock to the sensor components from moisture in the exhaust system. The ECM will not allow continuous HO2S heating until calibrated limits of time, temperature, and intake airflow have been reached. The ECM continuously monitors the HO2S heater current draw and operating state by briefly turning OFF the heater low side driver at regular intervals. A small reference voltage is present at the heater low control circuit. When the low side driver is commanded ON, the reference voltage is low, 2.6-4.6 volts. When the low side driver is commanded OFF, the reference voltage is high, close to battery voltage. If the ECM detects that the HO2S heater low control circuit voltage is between 2.6-4.6 volts when the heater is commanded OFF, DTCs P0030, P0036, P0050, or P0056 will set.

Each HO2S has the following circuits:
HO2S high signal
HO2S low signal
HO2S heater ignition 1 voltage
HO2S heater low control
CONDITIONS FOR RUNNING THE DTC
The engine is running.

CONDITIONS FOR SETTING THE DTC
The ECM detects that the HO2S heater low control circuit voltage is between 2.6-4.6 volts when the heater is commanded OFF, indicating an open HO2S heater circuit.

ACTION TAKEN WHEN THE DTC SETS
The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.

Check all fuses with a test light. Odd for all heaters to fail at once. Have each o2 tested for shorted heaters.

Roy
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Monday, May 6th, 2013 AT 5:11 PM

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